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Species Living in Big Oaks

Our refuge provides food and shelter for a wide variety of plant and animal species. The animal population includes over 230 species of birds, 46 species of mammals, 25 species of amphibians and 18 species of reptiles.


Of our 46 species of mammals, many are quite abundant. White-tailed deer are common throughout the refuge and our population of bobcats' have been increasing over the years. River otters were introduced on the refuge in 1996, and populations have increased since! Be on the lookout in winter, its the best time to see them!

Additionally, coyotes, wood chucks, red foxes, gray foxes, minks, and striped skunks appear on the refuge! Beaver impoundments are found in several places on the refuge. Our ecosystem engineers provide habitat for countless other species. Other species include Virginia opossums, raccoons, gray squirrels and fox squirrels. Hunting is allowed for squirrels and deer! There are roughly 11 species of bats including the federally-endangered Indiana Bat.

In 2016-2017 a black bear from Kentucky wintered on the refuge. In May 2017 sightings reported indicated that the bear left the refuge and returned to Kentucky.

Amphibians and Reptiles

An assortment of amphibians and reptiles inhabit the refuge. The streamside salamander is an exciting sight. Other salamanders include the spotted salamander, marbled salamander, cave salamander, and 9 other present species. The Crawfish Frog is a very important species that is state-endangered here on the refuge. Many actions are taken by refuge staff and volunteers to help preserve habitat and monitor this species. 11 other species of tree frogs and true frogs exists on the refuge. 

There is not many venomous snakes that occur on the refuge besides the Northern Copperhead. The southern black racer is a common sight, look out for them on the refuge roads! There are many other interesting snakes including milk snakes, Eastern hognose snakes and the state-endangered Copperbelly water snake. Eastern box turtles are another species to look out for on the refuge roads! Please, drive slowly and help our turtles cross the roads. 


Old Timbers lake is home to a variety of panfish including Crappie, Blue Gill, and sunfish. Largemouth Bass occur in addition to many other species of fish! 

White-tailed deer are among the most numerous mammal on the refuge.

River Otters were reintroduced on the refuge in 1996 and since then populations have flourished.

Eastern Wild Turkey are another popular and abundant game bird found throughout the refuge.

Bobcat kitten found in 2017 at Old Timbers Lodge.

Wood Ducks are one of the numerous waterfowl species here at Big Oaks.

Pileated Woodpeckers are a staple of Bid Oaks. They can be found throughout the refuge!

Eastern Box turtles are common, be careful driving as they may be crossing the road.

Great Blue Herons have been known to nest on the refuge.

Bobwhite quail are another game bird species found at Big Oaks.

Mudpuppies are a interesting and exciting site on the refuge.

Cave salamanders can be found on the refuge.

Wood frogs are one of the many amphibians that call the refuge home.

Coyotes are a an important species that call Big Oaks home.



Big Oaks National Wildlife Refuge has been designated a "Globally Important Bird Area".

Species of particular interest include the Henslow's Sparrows. These birds breed in the grasslands of the refuge. Kirtland's Warblers occur here and are federally-endangered. Bachman's Sparrow are also present and are state-endangered. 

Many waterbirds occur on the refuge. Great Blue Herons are known to nest, as well as Green Herons, Wood Ducks, Blue-winged Teal, and Mallards. Old Timbers lake hosts a variety of waterfowl species during migration. 

One can also find a variety of raptors, including a pair of breeding federally-threatened Bald Eagles at Old Timbers lake. Northern Harriers, Red-shouldered Hawks, American Kestrels are common on the refuge. Golden Eagles will utilize the grassland habitat during the winter. Many species of owls are also present. 

Woodpeckers can be found throughout the property along with Blue Jays, Carolina Chickadees, White-breasted Nuthatches , Northern Mockingbirds and Cedar Waxwings. The refuge is also home to many migrants- Cerulean Warblers, Worm-eating warblers, Northern Parula, Louisiana Warblers and more will occur!

Many game species, like wild turkey and bobwhite quail occur on the refuge! 

Endangered species

Big Oaks Conservation Society works in concert with, and under the direction of, Fish and Wildlife Refuge staff to enhance and assist with protection of these endangered species, and development and preservation of the habitat necessary for their continued survival.

State-endangered Species include:

  • Mammals- Evening Bat, Indiana Myotis (FE)

  • Birds- American Bittern, Osprey, Northern Harrier, Black Rail, King Rail, Yellow-crowned night Heron, Barn Owl, Short-eared Owl, Loggerhead Shrike, Sedge Wren, Golden-winged Warbler, Cerulean Warbler, Henslow's Sparrow

  • Amphibians- Crawfish Frog

  • Reptiles- Kirtland's Snake

  • Plants-  Broom Panic-grass, Clasping St. Johns wort, Climbing Fern, Elliptical Rushfoil, Mayland Meadow-beauty, Narrow-leaved Sunflower, Northern bog Clubmoss, Thread-like Naiad, Weakstalk Bulrush

A very important state-endangered species is the Crawfish frog (Rana areolata). This is a unique amphibian species that utilizes crawfish burrows and breeds in the many ponds across the refuge. Historically, this species would breed in buffalo wallows in Indiana. In place of these wallows,  impact areas where ordinances have exploded allowed for the creation of ponds that are now used by these frogs. 

Crawfish Frog

Henslow's Sparrow © Ron Austing

Blue-winged Warbler © Ron Austing

Cerulean Warbler © Ron Austing

Kirtlan'ds Water Snake

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Northern Harrier © Ron Austing

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